Add language setting and translation function

orangecanvas/application/settings.py

@@ -21,6 +21,7 @@
     Signal)
 
 from .. import config
+from ..utils.localization import get_languages
 from ..utils.settings import SettingChangedEvent
 from ..utils.propertybindings import (
     AbstractBoundProperty, PropertyBinding, BindingManager
@@ -274,6 +275,17 @@ def __setupUi(self):
         form = FormLayout()
         tab.setSizePolicy(QSizePolicy.Fixed, QSizePolicy.Fixed)
 
+        languages = get_languages()
+        if languages:
+            cm_lang = QComboBox(
+                objectName="combo-language",
+                toolTip=self.tr("Select the application language.")
+            )
+            cm_lang.addItems(languages)
+            self.bind(cm_lang, "currentText", "application/language")
+
+            form.addRow(self.tr("Language"), cm_lang)
+
         nodes = QWidget(self, objectName="nodes")
         nodes.setLayout(QVBoxLayout())
         nodes.layout().setContentsMargins(0, 0, 0, 0)

orangecanvas/config.py

@@ -364,6 +364,9 @@ def init():
      ("startup/load-crashed-workflows", bool, True,
       "Load crashed scratch workflows on startup"),
 
+     ("application/language", str, "English",
+      "Application language"),
+
      ("stylesheet", str, "orange",
       "QSS stylesheet to use"),
 

orangecanvas/utils/localization/__init__.py

@@ -1,3 +1,9 @@
+import os
+import json
+import importlib
+
+from AnyQt.QtCore import QSettings
+
 def pl(n: int, forms: str) -> str:  # pylint: disable=invalid-name
     """
     Choose a singular/plural form for English - or create one, for regular nouns
@@ -29,3 +35,36 @@ def pl(n: int, forms: str) -> str:  # pylint: disable=invalid-name
     if forms.isupper():
         word = word.upper()
     return word
+
+
+def get_languages(package=None):
+    if package is None:
+        package = "orangecanvas"
+    package_path = os.path.dirname(importlib.import_module(package).__file__)
+    msgs_path = os.path.join(package_path, "i18n")
+    if not os.path.exists(msgs_path):
+        return None
+    return [name
+            for name, ext in map(os.path.splitext, os.listdir(msgs_path))
+            if ext == ".json"]
+
+
+class Translator:
+    e = eval
+
+    def __init__(self, package, organization="biolab.si",
+                 application="Orange Canvas"):
+        s = QSettings(QSettings.IniFormat, QSettings.UserScope,
+                      organization, application)
+        lang = s.value("application/language", "English")
+        # For testing purposes (and potential fallback)
+        # lang = os.environ.get("ORANGE_LANG", "English")
+        package_path = os.path.dirname(importlib.import_module(package).__file__)
+        path = os.path.join(package_path, "i18n", f"{lang}.json")
+        if not os.path.exists(path):
+            path = os.path.join(package_path, "English.json")
+        assert os.path.exists(path)
+        self.m = json.load(open(path))
+
+    def c(self, idx):
+        return compile(self.m[idx], '<string>', 'eval')